Yay! Rushing! My old mare's favorite.
Set up two verticals (or x-rails, whatever you're comfortable with) with a few strides in between. Then try these exercises:
1) Trot up to the first one, jump it, then stop. Turn around, jump the fence, and stop, turn, jump, stop, turn, jump.... you get the idea. Make the "turn" portion work as well - turn on the forehand, haunches, etc, don't just turn around if you can avoid it. Once your horse settles down and realizes that he's just going to stop on the other side and starts coming back on his own, then you can trot to the next fence and let him jump it. As soon as he gets rushy again, go back to stopping and turning.
2) Trot to the first fence, but instead of going straight to the second jump, do a 20-m (or whatever works) circle back to the first fence. Mix things up. Add a circle between fences whenever you can, so your horse doesn't start thinking "oh, well now I can rush to the next fence!!!)
And other things you can work on without setting up those two fences:
3) Going back to your basic collect/extend exercises with Dressage really will help. Even if you have to take a few months off of jumping, I promise that dressage will help.
4) Try posting your canter.. seems silly, but you know how you can control your trot through posting? Apply the same thing to the canter.
5) Count your strides, and don't let your tempo speed up. Sometimes you can subconsciously be influencing your horse to speed up without thinking about it
6) Keep checking and giving!! Don't start a game of tug-of-war or you will lose. When the horse feels constant pressure on its mouth, it will think "okay I can take advantage of this, she's not paying attention to me!" ... if you keep your hands checking and giving, you are telling the horse that you are keeping your cool and are constantly reminding him that you're in control.
I'm sure I'll come up with more later
Hope this helps!